The studies are designed to assess the effects of aging on the adaptive changes in carbohydrate metabolism which occur during mitogen-stimulated activation of human lymphocytes. Current efforts are directed toward assessing changes in the overall energy and redox states of T-cells after stimulation. In addition, the molecular basis of enzyme changes is being elucidated. Triosephosphate isomerase exhibits a new isozyme pattern during blastogenesis, and the new isozyme seems to be due to the expression of a new gene. The basis of changes in other enzymes including phosphoglycerate kinase and pyruvate kinase is also under investigation.